Anoro is a LAMA/LABA combination and Arnuity is an ICS. Those two medications give you the standard three medications for COPD at the severe to very severe level. The only thing you might be missing is a "rescue inhaler".
You could, in theory take them indefinitely. Should you live long enough and your COPD progresses at a slow rate, the worst that could happen is that at some point you might not be able to inhale strongly enough to get the meds where they need to go, and you might need to switch to nebulized versions.

I also take both Arnuity in the morning and Anoro at night

Yes I am Anoro at night and Arnuity in the morning.